The subject invention relates to processes for making certain functionalized oxazolidinone compounds.
The subject invention involves processes for making compounds having the structure: 
wherein:
(a) R1 and R2 are each independently selected from hydrogen, alkyl, aryl and heterocycle, or R1 and R2 are attached to form a cycloalkyl, aryl or heterocyclic ring;
(b) R3 is selected from primary and secondary alkyl (xe2x80x94R6), xe2x80x94SO2xe2x80x94R4, andxe2x80x94C(O)NHxe2x80x94R5;
(c) R4 is aryl; and
(d) R5 is alkyl or aryl;
the process comprising a reaction step carried out in a reaction mixture, wherein an oxazolidinone having the structure: 
is reacted with an electrophile selected from R6-Br, R6-I, R4-SO2Cl, and R5-NCO; the reaction mixture comprising a non-protic and non-oxidizing solvent and potassium fluoride on alumina; and without the presence of a substantial amount of a strong base in the reaction mixture.
As used herein unless specified otherwise, xe2x80x9calkylxe2x80x9d means a hydrocarbon chain which is branched, linear or cyclic, saturated or unsaturated (but not aromatic), substituted or unsubstituted. The term xe2x80x9calkylxe2x80x9d may be used alone or as part of another word where it may be shortened to xe2x80x9calkxe2x80x9d (e.g., in alkoxy, alkylacyl). Preferred linear alkyl have from one to about twenty carbon atoms, more preferably from one to about ten carbon atoms, more preferably still from one to about six carbon atoms, still more preferably from one to about four carbon atoms; most preferred are methyl or ethyl. Preferred cyclic and branched alkyl have from three to about twenty carbon atoms, more preferably from three to about ten carbon atoms, more preferably still from three to about seven carbon atoms, still more preferably from three to about five carbon atoms. Preferred cyclic alkyl have one hydrocarbon ring, but may have two, three, or more, fused or spirocycle hydrocarbon rings. Preferred alkyl are unsaturated with from one to about three double or triple bonds, preferably double bonds; more preferably they are mono-unsaturated with one double bond. Still more preferred alkyl are saturated. Saturated alkyl are referred to herein as xe2x80x9calkanylxe2x80x9d. Alkyl unsaturated only with one or more double bonds (no triple bonds) are referred to herein as xe2x80x9calkenylxe2x80x9d. Alkyl unsaturated with one or more triple bonds are referred to herein as xe2x80x9calkynylxe2x80x9d. Preferred substituents of alkyl include halo, alkyl, aryl, heterocycle, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, amino, alkylamino, arylamino, arnide, alkylarnide, arylamide, formyl, alkylacyl, arylacyl, carboxy and its alkyl and aryl esters and amides, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano. Substituents of cycloalkyl also include cycloalkyl, aryl and heterocyclic rings which are fused or spirocycle with the initial cycloalkyl. Also, unsubstituted alkyl are preferred. An alkyl is bonded to another moiety at the xe2x80x9cattaching carbonxe2x80x9d of the alkyl. As used herein, xe2x80x9cprimary alkylxe2x80x9d means that the attaching carbon of the alkyl has two or three hydrogens bonded to it; xe2x80x9csecondary alkylxe2x80x9d means that the attaching carbon has one hydrogen bonded to it; and xe2x80x9ctertiary alkyl means that the attaching carbon has no hydrogens bonded to it.
As used herein, xe2x80x9cheteroatomxe2x80x9d means a nitrogen, oxygen, or sulfur atom.
As used herein, xe2x80x9calkylenexe2x80x9d means an alkyl which connects two other moieties, xe2x80x9cheteroalkylenexe2x80x9d means an alkylene having one or more heteroatoms in the connecting chain.
As used herein unless specified otherwise, xe2x80x9carylxe2x80x9d means an aromatic hydrocarbon ring (or fused rings) which is substituted or unsubstituted. The term xe2x80x9carylxe2x80x9d may be used alone or as part of another word (e.g., in aryloxy, arylacyl). Preferred aryl have from six to about fourteen, preferably to about ten, carbon atoms in the aromatic ring(s), and a total of from about six to about twenty, preferably to about twelve, carbon atoms. Preferred aryl is phenyl or naphthyl; most preferred is phenyl (Ph). Preferred substituents of aryl include halo, alkyl, aryl, heterocycle, hydroxy, alkoxy, aryloxy, thio, alkylthio, arylthio, amino, alkylamino, arylamino, amide, alkylamide, arylamide, formyl, alkylacyl, arylacyl, carboxy and its alkyl and aryl esters and amides, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano. Substituents of aryl also include cycloalkyl and heterocyclic rings which are fused with the aryl ring or rings. Also, unsubstituted aryl are preferred.
As used herein unless specified otherwise, xe2x80x9cheterocyclexe2x80x9d or xe2x80x9cheterocyclicxe2x80x9d means a saturated, unsaturated or aromatic cyclic hydrocarbon ring (or fused rings) with one or more heteroatoms in the hydrocarbon ring(s). Preferred heterocycles have from one to about six heteroatoms in the ring(s), more preferably one or two or three heteroatoms in the ring(s). Preferred heterocycles have from three to about fourteen, preferably to about ten, carbon plus heteroatoms in the ring(s), more preferably from three to about seven, more preferably still five or six, carbon plus heteroatoms in the rings(s); and a total of from three to about twenty carbon plus heteroatoms, more preferably from three to about ten, more preferably still five or six, carbon plus heteroatoms. Preferred heterocycles have one ring, but may have two, three, or more, fused rings. More preferred heterocyclic rings include those which are one ring with 5 or 6 carbon plus heteroatoms in the ring with no more than three ring heteroatoms, no more than two of which are O and S. Still more preferred are such 5- or 6-ring atom heterocycles with one or two ring atoms being O or S and the others being C; or with one, two or three ring atoms being N and the others being C. Such preferred 5- or 6-ring atom heterocycles are preferably saturated, unsaturated with one or two double bonds, or aromatic. Such preferred 5- or 6-ring atom heterocycles are preferably a single ring; or fused with a 3- to 6-ring atom hydrocarbon ring which is saturated, unsaturated with one double bond, or aromatic (phenyl); or fused with another such 5- or 6-ring atom heterocyclic ring. Heterocycles are unsubstituted or substituted. Preferred heterocycle substituents are the same as for alkyl.
As used herein, xe2x80x9cstrong basexe2x80x9d means an inorganic hydroxide base, alkyl-alkali metal (e.g., n-butyllithium), alkali metal hydride (e.g., sodium hydride), alkoxide salt (e.g., sodium methoxide), alkali metal amide (e.g., lithium diisopropyl amide), and the like.
As used herein, xe2x80x9csubstantial amountxe2x80x9d means a sufficient amount of a specified material such that it effects a subject invention process in a measurable way.
As used herein, xe2x80x9cnon-protic and non-oxidizing solventxe2x80x9d means a solvent that does not dissociate to provide a substantial and measureable proton concentration, and does not have substantial oxidizing potential. Protic solvents include, for example, water, methanol, ethanol, dimethylformamide and the like. Oxidizing solvents include, for example, dimethylsulfoxide, and the like.
As used herein xe2x80x9ccombinatorial libraryxe2x80x9d of compounds means a mixture of related compounds or a group of individual compounds, e.g. in separate wells of a reaction block, made substantially simultaneously by substantially the same process using a mixture of or individual related reactants to obtain related compounds.
The subject invention processes involve the use of a solid supported reagent for the preparation of functionalized oxazolidinones, either individually or in libraries. As a class, oxazolidinones have been shown to possess a wide range of biological activity, including antidepressant, antihistaminic, antiftingal, antihypertensive, and antibacterial activity. A brief examination of the literature reveals that most common methods for the preparation of functionalized oxazolidinones require the use of strong bases (i.e. n-BuLi, NaH, etc.) and an aqueous work-up. The preparation of combinatorial libraries of oxazolidinones is greatly simplified by the subject processes which preferably avoid both of these steps. The functionalization of oxazolidinones in the 2-position is accomplished using potassium fluoride on alumina (KF/Al2O3) as a base in the presence of a suitable electrophile.
In addition to the preparation of single compounds, the subject invention processes are useful for the preparation of combinatorial libraries through the use of a reagent on solid support (KF on alumina). This approach, which sits between conventional solution phase chemistry and resin bound techniques, shares several advantages of both fields. As with solid phase synthesis, excess support bound reagent can be used to drive reactions to completion and then be removed by filtration, avoiding cumbersome work-ups. Unlike resin based chemistry, however, the target compound is not covalently bound to the solid support, so monitoring of the reactions and analysis can be accomplished using standard methods (thin layer chromatography, solution 1H NMR, etc.). Finally, the products are isolated by filtration and removal of the solvents, eliminating the need for the cleavage step required in solid phase preparations.
Processes of the subject invention involve preparation of functionalized oxazolidinones having the structure: 
In structure (1), R1 and R2 are each independently selected from hydrogen, alkyl, aryl, and heterocycle, or R1 and R2 are attached (R1/R2) forming a cycloalkyl, aryl, or heterocyclic ring. Preferred R1 and R2 are independently selected from hydrogen, alkyl, and aryl. Preferred alkyl R1 and R2, and non-aromatic rings that are R1 or R2 or R1/R2, are unsubstituted or substituted, preferably with: fluoro, chloro, alkyl, aryl, heterocycle, alkoxy, aryloxy, alkylthio, arylthio, formyl, alkylacyl, arylacyl, alkyl and aryl esters, sulfo, alkylsulfo, arylsulfo, sulfmo, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro and cyano; more preferably with: alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, alkyl and aryl esters. Preferred aryl and aromatic heterocycle R1, R2 and R1/R2 are unsubstituted or substituted, preferably with: halo, alkyl, aryl, heterocycle, alkoxy, aryloxy, alkylthio, arylthio, formyl, alkylacyl, arylacyl, alkyl and aryl esters, sulfo, alkylsulfo, arylsulfo, sulfmo, alkysulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphophino, arylphosphino, nitro, and cyano; more preferably with: halo, alkyl, alkoxy, aryloxy, alkylthio, arylthio, alkyl and aryl esters, and nitro.
In structure (1), R3 is selected from primary and secondary alkyl (R6), SO2-R4, and xe2x80x94C(O)NHxe2x80x94R5. R4 is aryl. R5 is alkyl or aryl.
R6 is a primary or secondary alkyl, preferably having from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, more preferably still from I to about 4 carbon atoms. Such alkyl R6 is unsubstituted or substituted, such substituents preferably being selected from fluoro, chloro, alkyl, aryl, heterocycle, alkoxy, aryloxy, alkylthio, arylthio, formyl, alkylacyl, arylacyl, alkyl and aryl esters, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro and cyano; more preferably from alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, alkyl and aryl esters, alkylphospho, arylphospho, and cyano.
R4 is aryl, preferably phenyl. Such aryl R4 is unsubstituted or substituted, such substituents preferably being selected from halo, alkyl, aryl, heterocycle, alkoxy, aryloxy, alkylthio, arylthio, formyl, alkylacyl, arylacyl, alkyl and aryl esters, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano; more preferably from halo, alkyl, alkoxy, aryloxy, alkylthio, arylthio, alkyl and aryl esters, alkylacyl, and arylacyl.
When R5 is alkyl, it is a primary, secondary or tertiary alkyl, preferably having from 1 to about 12 carbon atoms, more preferably from 1 to about 8 carbon atoms, more preferaly still from 1 to about 4 carbon atoms. Such alkyl. R5 is unsubstituted or substituted, such substituents preferably being selected from halo, alkyl, aryl, heterocycle, alkoxy, aryloxy, alkylthio, arylthio, formyl, alkylacyl, arylacyl, alkyl and aryl esters, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano; more preferably from alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, alkyl and aryl esters.
When R5 aryl, the aryl is preferably phenyl. Such aryl R5 is unsubstituted or substituted, such substituents preferably being selected from halo, alkyl, aryl, heterocycle, alkoxy, aryloxy, alkylthio, arylthio, formyl, alkylacyl, arylacyl, alkyl and aryl esters, sulfo, alkylsulfo, arylsulfo, sulfino, alkylsulfino, arylsulfino, phospho, alkylphospho, arylphospho, phosphino, alkylphosphino, arylphosphino, nitro, and cyano; such substituents preferably being selected from halo, alkyl, alkoxy, aryloxy, alkylthio, arylthio, alkyl and aryl esters, and nitro.
The processes of the subject invention comprise a reaction step wherein an oxazolidinone having the structure: 
is reacted with an electrophile selected from R6-Br, R6-I, R4-SO2Cl, and R5-NCO. R1, R2, R4, R5 and R6 are as defined hereinabove.
The above reaction step is carried out in a reaction mixture comprising solvent which non-protic and non-oxidizing. Preferred solvents are selected from dichloromethane, dichloroethane, chloroform, ethyl acetate, 1,4-dioxane, tetrahydrofuran, dimethoxyethane, and acetonitrile. When the electrophile R6-Br or R6-I is a reactant, more preferred solvents are selected from acetonitrile, 1,4-dioxane, tetrahydrofuran, dimethoxyethane, and ethyl acetate. When the electrophile R4-SO2Cl is a reactant, more preferred solvents are dichloromethane and dichloroethane. When the reactant R5-NCO is used, more preferred solvents are selected from dichloromethane, chloroform, ethyl acetate, and 1,4-dioxane.
The reaction mixture comprises potassium fluoride on alumina. Potassium fluoride on alumina (KF/Al2O3) is typically from about 10% to about 60% KF, preferably about 40% KF. The amount of KF/Al2O3 present during the reaction step is preferably from about 6 equivalents to about 15 equivalents per equivalent of compound (2), more preferably from about 10 equivalents to about 12 equivalents per equivalent of compound (2).
In the above reaction step, the amount of electrophile reacted with compound (2) is typically from about 0.9 equivalent to about 1.5 equivalents, more preferably about 1.0 equivalents.
The above reaction step is preferably carried out at a temperature of from about 0xc2x0 C. to about 95xc2x0 C., more preferably at a temperature of from about 20xc2x0 C. to about 80xc2x0 C., more preferably still at about room temperature (about 25xc2x0 C.). The above reaction step is preferably carried out for a period of from about 5 h to about 72 h, more preferably from about 10 h to about 36 h, more preferably still for about 24 h.
The above reaction step is preferably carried out without the presence of any substantial amount of a strong base in the reaction mixture, preferably less than about 0.15 equivalent strong base, more preferably less than about 0.01 equivalent, still more preferably with no strong base in the reaction mixture.